Huh, I kind of figured she'd appeal to the friends of the 4 accusers. "So, I've been flirting with them and you all know them individually well enough to know they aren't ones to lie... yet, none of you ever saw me interact with them? None of you remember any of the 4 of them ever talking about me or my interest in them prior to now? I'm the crown prince's fiancé and a duke, and they never talked about this sudden interest I was showing them"
I guess it depends on how long she had the memory manipulation in place, if it's very recent that would hold up, but if it's been in place for awhile that could backfire if they had been talking to their friends about the made up events...